Speed indicator for boats



Dec. 9, 1941. R. T. FISHER ET AL SPEED INDICATOR FOR BOATS Filed June 8, 1939 477m ,l m

ATTCRNEYS Patented Dec. 9, 1941 SPEED INDICATOR Fon nous Richard T. Fisher and Robert H. Pierce, Duxbury, Mass., assignors to The Fisher-Pierce Company, Incorporated, a corporation of Massachusetts Application June s, '1939, serial No. 278,015

(o1. 'za-iss) 4 Claims.

This invention relates to speed indicating instruments, particularly those adapted for use in small boats, such as small sail boats or motor craft. It more particularly relates to a speedometer for small vessels having advantages of cheapness and ruggedness of construction and accuracy of indication.

It is an object of this invention to provide a small boat speedometer having means for translating relative motion of the boat through the water into visual observable data, which means shall comprise an actuating device of simple cheap construction, which presents practically no impeding surface to the water through which the boat moves and which is easily and simply accessible and cheaply replaced in the event of damage from any obstruction with which the boat may come in contact.

It is a further object of the invention to provide such a construction which may be simply removed while the boat is in motion or moored, for repair or storage purposes.

Further objects and advantages of the invention will appear from the following description and drawing in which Figure 1 is a view in front elevation of one embodiment of the speedometer of this invention as applied to the hull of a boat;

Figure 2 is a somewhat enlarged view. partly in front elevation and partly in section of the speedometer shown in Fig. 1;

Figure 3 is a sectional view taken through the line 3-3 of Fig. 2, looking in the direction of the arrows and;

Figure 4 is a` section through the line 4-4 of Fig. 3, looking in the direction of the arrows.

Referring more particularly to the drawing, a portion of the hull of the boat which is preferably taken well below the water line and near the keel is shown at II having a hole I2 drilled therethrough. Inserted in the hole I 2 is a mounting tube I3, the lower end of which is approximately ilush with the outside of the hull II and i the upper end of which extends into the boat to a 'Ilhe speedometer proper includes a tube 22 longer tnan and adapted to be inserted in the mounting tube I3 and of a size to permit relatively snug sliding relationship between the two tubes. Tne clamp I4, suitably secured on the tube 22 by means of screw II which adjustably holds ears 2U, or other convenient means, has a pin I6, which is adapted to drop into slot I5 in the tube I3 to fix the dial in proper position for observation. The tube 22 preferably is mounted to terminate at its lower end slightly above or flush with the mounting tube I3 and the bottom of the hull of the boat. The upper end of the tube 22 is lixed to a collar support 23, which also holds the indicating head 2'9 of the apparatus. Tube 22 is secured to the support 23 by means of clamp 24 which is similar to clamp I4 above described or in any other suitable manner. The various parts of the instrument, particularly the parts which will be exposed to air or water, may preferably be formed of some non-corrosive metal such as bronze or the like.

The general plan of speed indication includes an arm or other small water engaging device placed outside of the hull of the boat, which arm is adapted to be deilected by the pressure of the lwater; this deection is adapted with proper calibration and damping to be translated into visual data. It will be seen from the following description that the invention may be adapted to instruments of various natures for indicating the relative speed oi various uids past a given point.

It is a particular advantage of the construction of this invention that the device which extends outside of the hull into the water is of extremely small cross section, a wire of less than $4; inch diameter and of approximately the same cross section throughout being satisfactory. though it will be understood that wires or vanes of other sizes and shapes may be adapted to this use. We presently prefer to use a wire of approximately 116 inch diameter. It can be seen that the small surface of opposition to movement of the boat through the water will have no eiect upon the Velocity of the boat.

A further advantage of this construction may be found in the fact that a wire may be used having no greater rigidity than that required to withstand the pressure of the water, so that when an obstruction is met, the result is only bending of the wire from its proper position rather than destruction of expensive vanes, iins or the like. Even if the encountered obstruction should damage the wire beyond rebending, the cost of rethe bottom of the boat and be rounded or stream- 1 lined. 'Ihe block 25 is recessed at 21 to provide for the mounting of the actuating means, which include a plate 28 mounted for pivotal movement on the shaft 30. Spacing washers 34 may also be mounted on the shaft 30 to prevent lateral movement of the plate 2'8. The plate 28 is limited in rotatory movement about the pivot 30 by means of the pin 35 (see 3), permanently mounted in the block 25, which passes through the slot' 36, formed in the plate 28. The end of the plate 28, remote from the shaft 30, is bifurcated as at 38.

Thev means forl translating the movement of the boat through the Water into mechanical movement, comprises the pin or wire 44 which is rigidly mounted between the bifurcated por- 4I, which may be tightened to draw the sides of the plates against the Wire. It will be understood that as the force of the water acts against the pin 44 the plate 28 is moved about the pivot 30, as is illustrated'in dotted lines in Fig. 3. The movement of the wire 44 and plate 28 may suitably be transmitted to the indicating device by means of the tensioned wire 45,- which wire may be very light in construction since only its tensioned force will be relied upon to operate the instrument, and since no damage can result to this wire or to the indicating apparatus itself due to movement of the platel 28, as unusual movement thereof is prevented by the pin and slot construction 35, 36. No matter what obstruction may be encountered by the vessell the damage resulting from a blow on the wire 44 cannot be transmitted beyond the plate 28.

The indicating portion of the instrument may be encased in the indicating head 29'having a 'back portion 14 secured to the upper portion of the supp'ort 2'3 and thus rigidly mounted in relation to the tube 22. The head also includes the annular or other conveniently shaped side wall 13 which may be integral with the back portion 14. At the front portion of the head the bezel 1| holds the crystal 10.

AThe wire 45 extending from the plate 28 passes through the tube 22 and support 23 and through the aperture 11 in the side wall 13 of the head and is secured at its upper end to the arm 46 of a bell crank 50, which is mounted on the shaft 41 supported in the instrument head. On one end of the shaft 41 is rigidly secured the indicating hand 49, whereby the rotation of the shaft moves the hand over the scale 55 on the dial 5I, thus indicating the speed of movement-of the vessel. The shaft 41 is supported at its forward end by the bar 19 which is attached to the back 14 of the case. The other end of the shaft 41 may conveniently be mounted in the socket 52 of the threaded screw 53. The screw 53 passes through the supporting bracket 23 and through the back 14 of the case and may be locked in position by nut 54, thus holding the case and bracket in permanent rigid relationship. To the `other arm 56 of the bell crank 50 is secured the calibrating spring 51, which spring is adapted to modify the motion imparted to the pointer 49 into appropriate units of movement on the scale 55.

Because of slight and immaterial variations of the force of water against actuating pin 44, the movement of the indicating hand 49 would tend to be somewhat jerky and unstable and it is thus desirable to provide means for damping the rotation of the shaft 41. These means may be provided by any convenient apparatus, the apparatus here shown being presently preferred by us, and comprising a chamber 60 through whichvthe shaft 41 passes, and a vaned wheel 6I rigidly secured to the shaft 41 and rotating therewith. Y

The wheel 6I may be conveniently and simply constructed by cutting notches in the periphery of a round flat disc and by turning the portions of the disc adjacent the notches to a position approximately perpendicular to the plane 4of the disc.

- tions'of the plate and clamped therein by screw The chamber 60 is preferably partially filled with relatively heavy oil 63 the normal level of the oil being below the shaft 41. It will be understood that any possible erratic movement of the shaft 41 will thus be dampened by thev inertia of thevaned wheel 6I rotating in the oil. Access to the oil chamber for introduction of theoil may be had by any means such as the aperture 66, which is preferably provided in the threaded screw 68 extending through the bracket 23 and the casing 14 and into the oil chamber 60. The oil aperture may conveniently be closed by the threaded plug61.

In order to prevent the leakage of oil from the chamber 60 annular baiiles may be provided about the shaft 41, baflles 65a and b being rigidly secured to the wall of the chamber and baille 65c being secured to the shaft and rotating therewith. It will be seen that preferably the rotatingv baille -65e does not'extend further toward the aperture 59 in the chamber 60 through which the shaft 41 extends than the innermost end of the non-rotating baille 65h. This construction has been found to permit the shaft to be extended through the aperture 59 without any packing whatsoever and without leakage of oil in any position of the instrument.

The operation and use of the instrument are quite simple. The indicating device and tube 22 are removable from tube I3 as a unit so that when the boat is not being used the speedometer as a whole may be stored inea convenient locker and the top of the tube I3 may, if desired, be closed with a suitable plug (not shown). The complete removability of the instrument without the necessity for lne adjustments or the like is, of course, a distinct advantage and will result in a long and useful life of the instrument as a whole. lIihe instrument may be withdrawn from the mounting tube at any time during use to revmove anything fouling the pin or to straighten or replace the latter if damaged.

Owing to the fact' that the angularity` of the wire 44 with respect to the direction of the movement of the wire through the iluid is greater at higher speeds and due also to the angular relation between the wire and levers, it is possible to use a relatively open scale in lower speed and secure relative uniformity in distances of travel of the indicator between various units of speed.

While we have illustrated and described in detail one preferred form of our invention, it is to be understood that vchanges may be made therein and the invention-embodied in other but intend to cover our invention broadly in whatever form its principle may be utilized.

We claim:

l. A boat speedometer comprising a tube, an indicator mounted at the upper end of said tube, and a pivotally, mounted member at the lower end of said tube, said pivotally mounted member carrying adjustable clamping means, and a vane in the form of a 'wire of uniform diameter held by said clamping means and capable of being adjnsted longitudinally, and operative connections between said pivotally mounted member and said indicator passing through said tube.

2. A boat speedometer comprising a tube carrying an indicator at the upper end thereof, and having a fitting at the lower end thereof, the outer diameter of which does not exceed the outer diameter of the tube, said tting being recessed, a bock pivotally mounted in said recess, means for positively limiting the pivotal movement of the block, operative connections between said pivoted block and said indicator passing through said tube, and a water contacting vane iixed to said pivoted block, said vane being in the form oi a thin bendable member of suicient rigidity to withstand without substantial distortion the pressure of water caused by the movement of the boat, but being suiciently weak to bend upon encountering an obstruction, without forcing the pivoted block beyond its predetermined normal limits of motion.

3. A boat speedometer comprising a tube having an indicator mounted on the upper end thereof and having a fitting attached to the lower end thereof, said iitting having a recess extending the rethrough, a block mounted in said recess to pivot about a horizontal axis, operative connections between said block and said indicator passing through said tube, a stop on the fitting engaging portions of said block to limit the pivotal movement thereof, the free end of said block being bifurcated, a slender water engaging vane having its upper end projecting between the bifurcations of said block, and means for clamping said bifurcations against said vane to removably and `adjustably secure the same to said block. l

4. A boat speedometer comprising an outer tube having a fitting thereon adapted to be fixed in the hull of a boat below the water line, and a removable inner tube adapted to be carried in said outer tube, said inner tube carrying a pressure responsive vane at the bottom thereof and having an indicator head at the top thereof, an indicator in said head, and operative connections between said vane and said indicator passing through said inner tube, said indicator including a shaft supported in said indicator head to turn about a normally horizontal axis, an indicating member fixed to said shaft, a damper chamber mounted in said indicator head and surrounding a part of said shaft, said chamber being normally lled with a damper liquid to a level below said shaft, the partof the shaft carrying said indicator projecting freely through an opening in a wall of said damper chamber, a vaned member rigidly secured to said shaft within said chamber and dipping into said damper liquid, a baiiie ring mounted on the wall` of said damper chamber around the opening therein through which the shaft passes, said baiiie ring projecting a substantial distance away from said wall towards the interior of the damper chamber, and a baiiie ring iixed to said shaft and cooperating with said fixed baffle ring to prevent leakage in any position of the instrument of damper liquid from the chamber through the opening in said wall through which said shaft projects.

ROBERT H. PIERCE. RICHARD T. FISHER. 

